Complete mitochondrial genome of an abyssal cusk-eel (Ophidiiformes: Ophidiidae).

Zugmayer, 1911 is an abyssal fish species inhabiting depths exceeding 3,000 m. We successfully sequenced and characterized the complete mitochondrial genome of , which represents a closed circular molecule of 16,646 bp with a GC content of 48.98%. Phylogenetic analysis of Ophidiiformes based on whole mitochondrial genome sequences demonstrated that forms a sister group with while supporting the polyphyly of Bythitidae as well as the paraphyletic status of Ophidioidei. As the first report of a complete mitochondrial genome for , this study provides valuable genomic resources for investigating deep-sea adaptation mechanisms in Ophidiiformes and contributes to our understanding of evolutionary patterns in abyssal teleost fishes.